The present invention pertains generally to elongate panels joined at their sides to provide the exterior of building walls and roof structures.
Well known in the building construction is the use of sheet metal panels shaped along their marginal edges for interlocking engagement to provide a joint between panels. A wide variety of panel edge configurations are disclosed in the prior art. Such configurations are typically formed in a continuous manner on roll forming machines.
Panel securement to roof or wall members of a building entails the prior installation of clips on roof members with the clips shaped to engage edge or rib surfaces for panel retention. A problem encountered with the use of clips results from the accuracy necessary in clip installation. For example, U.S. Pat. No. 4,285,182 is directed toward locator strips for clip spacing, while U.S. Pat. Nos. 4,400,922 and 4,486,998 disclose a clip directed toward compensating for "rib-to-clip and joint-to-clip misalignments" and a clip to overcome rib spacing problems.
U.S. Pat. No. 4,406,106 discloses a clip, a pair of laterally projecting "tongues" to which panel ribs, of corresponding shape, are flexibly engaged.
U.S. Pat. Nos. 4,466,224 and 4,467,582 disclose clips for panel securement with the clips having "wings" which flex inwardly during panel attachment and thereafter flex outwardly to seat against the base of a panel rib. U.S. Pat. No. 3,606,720 discloses a clip for securing a centrally disposed panel rib. This patent disclosure is of interest in that it discloses the marginal edge configurations of a panel which are shaped to provide cooperating inclined surfaces to effect "camming" during downward pressure being exerted on the outer panel edge during formation of a joint between adjacent panels.
In addition to serving to attach a panel to a roof or wall member clips serve to reinforce panel ribs against externally applied loads but only at widely spaced intervals leaving the rib segment between clips susceptible to damage as, for example, by being stepped on. In addition to the above noted negative aspects of utilizing clips at precisely spaced intervals for panel to roof securement, such clips are typically of costly manufacture.
While some prior art roof panels have dispensed with the necessity of clips, such panels require that a continuous roof or wall underlayment be in place prior to panel installation on same. The cost and installation of such an underlayment is a significant factor in the overall cost of such a roof.
Existing panel designs rely on interengageable ribs formed along the sides of adjacent panels to form a joint. Such engaged ribs form a joint which is susceptible to damage as when an installer or worker inadvertently steps on such a joint. Such panel designs rely on clips on 4 and 6 foot centers with the span of the joint between clips being susceptible to damage as noted above.